1. Field of the Invention
The present invention relates generally to hybrid capacitors, and particularly to high energy density and high power density hybrid capacitors employing cellular honeycombed separator structures with non-uniform cell geometry, and to methods for producing the same.
2. Technical Background
Ultracapacitors, also commonly referred to as electric double layer capacitors, are potentially useful for many applications where pulse power or power leveling is desirable or required. These applications range from small devices such as cell phones to large devices such as hybrid vehicles.
Where a device having power densities similar to an ultracapacitor but with increased energy density is desired, hybrid capacitors have been explored. In an ultracapacitor as used herein, the electrodes are non-galvanic, meaning that they do not undergo faradaic reactions in the associated electrolyte solution within the intended operating voltage range of the device. A hybrid capacitor, as used herein, includes at least one galvanic electrode, in addition to at least one non-galvanic electrode.
The energy and power density of hybrid capacitors known today is not as high as would be generally desired for various applications, including hybrid vehicles. A durable, easily manufactured, high energy density and/or high power density device is thus desirable.